The present invention broadly relates to an improved scrubbing apparatus for extracting contaminating particulate matter entrained in a gas stream employing a liquid washing medium. The principles of the present invention are particularly applicable, but not necessarily restricted to the removal of entrained paint particles from the exhaust air stream from paint spray booths to provide an environmentally acceptable effluent while simultaneously recovering the paint overspray for processing in a paint reclamation system.
A variety of scrubbing devices have heretofore been used or proposed for use in association with paint spray chambers or booths. While such devices have provided satisfactory operation in the past, the imposition of more stringent environmental specifications on the maximum permissible levels of particulate matter in the exhaust effluent has necessitated further development of improved designs to increase the effectiveness of such devices in capturing and extracting large proportions of the entrained particulate matter. A continuing problem associated with scrubbing devices of the types heretofore known has been the lack of flexibility and versatility in adapting such devices to changes in the paint formulations and spray loading characteristics as occasioned by the development and commercial use of improved coating materials and the use of robot paint application systems along selected sections of a spray booth tunnel.
In the painting of automobile bodies, for example, it is conventional practice to sequentially apply one or more prime coatings followed by one or more finish or top coatings to the automobile body employing a series of individual spray booth tunnels separated by intervening bake ovens for curing the coating. The different formulations of such individual paint systems produce different overspray characteristics and capture tendencies of the paint particles whereby the scrubbing system for each such spray booth tunnel must be tailored to achieve optimum extraction of the contaminated particulate matter. Changes in a specific coating sequence and/or modifications in one or more of the individual paint systems employed necessitates a readjustment of the scrubbing device to restore it to optimum operation under the specific conditions encountered. While some scrubbing devices of the types heretofore known have suggested the use of movable baffle components to vary the scrubbing characteristics to accommodate variations in the paint spray parameters encountered, such devices have been less than satisfactory due to the tendency of such movable mechanisms to become encrusted with a layer of the particulate material rendering them inoperative and necessitating frequent time consuming and costly cleaning operations to restore them to satisfactory operating condition.
There has, accordingly, been a long felt heretofore unfilled need for an improved scrubbing device incorporating a low energy, high efficiency scrubbing mechanism which is readily replaceable to adapt the device to any particular scrubbing condition thereby attaining optimum efficiency and versatility. Additionally, the replaceable nature of the scrubbing mechanism facilitates periodic cleaning and service of the unit minimizing down time and labor associated with such periodic servicing. The scrubbing device of the present invention is also readily adaptable to a modular construction enabling a combination of the desired number of modules to provide a spray chamber tunnel of the desired length consistent with the spray operation to be performed providing for still further versatility and economy in the manufacture, installation and use of the device.